Loud-speaker with expanding horn unit



Sept. 25, 1951 G. L. CARRINGTON LOUD-SPEAKER WITH EXPANDING HORN UNIT Filed March 24, 1947 h cm ,WM MN W. H w h WNW f 2 5 9 8 Q nu r W0 Q E E wv Kr; NH

u u HI HI u HI H J tromagnetic type. aspects and corresponding purposes and accom- Patented Sept. 25, 1951 A UNITED STATES PATENT OFFICE c "LOUD-SPEAKER WITH EXPANDING HORN UNIT George L. Carrington, Encino, Calif., assignor to Altec Lansing Corporation, Los Angeles, Calif., a corporation of Delaware Application March 24, 1947, Serial No. 736,636

1 This invention relates to speakers of the elec- The invention has several rigid diaphragm or dome which is directly hysically connected with the actuating element,-

Which is here the vibrating voice coil. This central diaphragm is made in such form as to be substantially rigid in itself and is accordingly preferably made inthe form of a spheric dome.

J Due to its characteristics, and due to its direct physical connection with the voice coil, it vibrates as a rigid unit and is particularly effective'in radiating the higher frequencies. The lower fre quencies are radiated both by the central dome and by the surrounding conediaphragm.

2 Claims. (01. 181-31) shown as attached to the back of the case. As here illustrated the field magnet system includes a permanent magnet, although an electro-magnet of course may be used. As illustrated, the permanentmagnet is shown at H with a front central pole piece I2 at one end and with a surrounding annular pole piece l3 magnetically connected with the other end of magnet by members 4 and I5 forming the usual magnetic circuit. The annular voice coil is shown at IS in the annular gap between pole pieces I2 and I3. As here shown the voice coil is mounted on and carried by a light tubular member 20, constructed of any suitable material and usually made of I magnetically energized actuating element of the In such a speaker, a horn unit, preferably of the multi-cellular exponential type may be and preferably is associated with the or dome diaphragm.

The cone diaphragm, which is connected at its inner periphery with the voice coil, is relatively flexible and its outer portions partake less in central rigid the vibratory motion of the voice coil as the frequency increases. It is consequently desirable to increase the efiiciency with which the energy from the central rigid dome is transmitted and that is effected b associating a horn with that 1 central member.

Such a combination of central rigid diaphragm and surrounding cone, particularly when it includes the efliciencyincreasing horn, provides a speaker unit of relatively small bulk and simple structure which in performance approaches closely to the performance of much larger and more complicated combinations.

The accompanying drawings show my present preferred form which is illustrative of the various features of my invention. In those drawings,

Fig. l is a half-elevation, half-central-section showing my preferred design;

Fig. 2 is a fragmentary front elevation at a reduced scale; and

Fig. 3 is an enlargement of certain portions of Fig. 1.

speaker.

Voice coil tube 20, in the design shown in the drawings, extends forwardly from voice coil IS a short distance and carries the rigid diaphragm 2| at its forward edge.

Although diaphragm 2| may be flat or of other shape, it is preferably spherically dome-shaped with its convex face outward, as shown. The diaphragm is composed of some suitable stiff and light material, for instance of some suitable plastic or of a metal such as aluminum or alloy. The dome and tube 20 are preferably of substantially equal diameters and are rigidly secured to ether at their edges at 22 by cementing or similar attachment. Thus assembled, the dome 2 tubular member 20, and voice coil I6 form a substantially rigid unit which will vibrate substantially as one rigid whole in a direction along the axis of the speaker. Due to the rigidity of the connection between dome 2| and voice coil Hi the dome may be regarded as being rigidly physically attached directly to the voice coil itself. The axial forward extent of tube 20 from the voice coil may be less than that shown in the drawings and may be substantially completelyeliminated, so that the dome would then be actually directly connected with the voice coil. The forward extent of tube 20 is however preferred; as that provision spaces dome 2| forwardly from pole piece l2 and also facilitates the connection of cone diaphragm 25 with the tube. The space behind dome 2| is vented by holes 20a through tube 20.

Cone diaphragm 25 may be of any of the usual forms and structures and it is connected with tube 20 independently of the comiection of dome 2| to that tube. With such independent connections each of the diaphragms 2| and 25 are actuated directly from the voice coil. As here shown the cone diaphragm has a flange 26 at its inner periphery cemented to the outer surface of tube 20. It is also held to the tube by the inner flange 21 of an annular member 28 which has its outer periphery secured at 29 to casing Ill. The function of annular'member 28 is to centertube 2!]; and the voice coil in proper concentric relation inthe magnet gap and at the same time to allow free vibratory movement of those parts along the axis. of any suitable construction; it .is here shown as a thin annulus composed of a molded plastic.

The parts so far described may compose the complete dual-diaphragm speaker; both-onthe diaphragms 25 and 2| radiating directlywithout the intervention of a horn. It is preferred, however, to associate a multi-cellular exponential horn with the dome diaphragm 2| in the manner shown in the drawings. The multi-cellular horn unit 30, as shown here, may comprise any suitable number of cells, shown as six. The .unit ispreferably antintegral one-formed. of;some suitable molded plastic. The inner ineput end-of the horn unit is secured in a mountingplate, 3 and a faceplate 32 is also secured totthe-rear face of mounting plate .3] surrounding the inner input endof .thehornrunit. The three parts may be secured together in any suitable manner. As here-shown faceplate 32 is secured to mounting plate 3| by SCIBWSz33'; and the inner intake end of .unit '302 is secured-within both plate 3| and plate 32by cementing.

Theinner facev of: the f inner: endof the horn, and" theinner face oftfaceplate 32 are both formed to agsingle spheric surface; 35 which is concentric withandsp'aced a short distance forward'ofdomediaphragm- 2|, asshown'in the drawings. The outer diameter of face plate 32 is preferably aboutzt-hesame astheexternal diameterofdome 2!. Thus the; arrangement is such.that,aathin"spheric:-spa ce is, enclosed by face 35 of the horn unit directlyforward of'the, convex face of ,dome: diaphragm 2|. Plates 43| and 32, oratleast face-platen, maybe considered as forming-a part of-the horn unit; so that, the

spheric; surface-35 may--be considered as being formeddirectly on the inner end of-thehorn unit. The-horn unit'is supportedinthe casing by a pair of, supports, each shown as comprising a spacer tube 40 anda bolt or-screw 4|; supporting the supporting plate 3| from the casing. As hereshown, the supporting units 40, 4| connect directly-with annular casing member 42 upon which. themagnet system is-directly mounted.

The-two supportingrunitslll, 4| pass through holes 28a provided in, member-28.- In order to allow member 28 freedom-of movement, the holes 28a are made large enough to provide clearance.

Clearance holes 25arare also provided in cone diaphragm 25to pass the supporting units. To

Member 28 may he and a surrounding cone diaphragm which radiates directly; and preferably with an efficiency increasing horn associated with the central rigid diaphragm. The features of preferred constructional detail which have been set out in the foregoing detailed description are typical only and are not to be taken as limiations on my invention except as the following defining claims may so state.

I claim:

1. In a speaker of the character described, a single voice coil element of tubular form including a single voice coil adapted to operate in an annular magnetic-gap and the element having an outer endbeyond the gap, a relatively small and a relatively large diaphragm actuated by the voice coil element, the relatively small diaphragm consisting solely of a rigid dome having an outward convex radiating face of substantially the same diameter as the tubular voice coil element and:having its peripheral edge directly and rigidly mounted onthe outer end of that element, and the larger diaphragm consisting solely of a relatively flexible annular cone with an outer radiating'face directly open to free space,said annular cone coaxially surrounding the tubular voice coil element and the. rigid diaphragm and'having its inner periphery directlyand rigidly attached to the outer end portion of the tubular voice coil element, all whereby the smaller rigid diaphragm and the inner peripheral edge ofv the cone diaphragm are vibrated together at all frequencies as arigid unit with the voice coil, and an outer fixed casing structure behind. and surrounding the larger cone diaphragm, anexpandinghorn unit, supported with its, open intake end inclose juxtaposition to and outward of the outer. radiating face of the smaller rigiddiaphragm, and supportingmeans for thehorn unit comprising mounting studs-located. outside the voice coil element and extendinggenerally parallel to the axis of that element freely through openings provided inthe cone diaphragm, theinner ends of said studs being rigidly mountedon the casing structure behind the cone diaphragm and the outer ends, outward of the cone diaphragm, rigidly carrying the horn unit.

2. Speaker structure as defined in claim 1, and also including an annular flexible sealing diaphragm secured at its inner edge to the horn unit and. at itsouter edge to the outer face of the cone diaphragm and lying outward of the outer ends of the supporting studs, and another annular flexible sealing diaphragm lying behind the cone diaphragm with .its inner peripheral edge connectedwith thevoice coil element, its outer edge secured to the casing structure, and having openings which closelyflt the supporting studs.

GEORGE L. CARRINGTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,869,665 Chann Aug. 2, 1932 1,917,012 Blattner July 4, 1933 2,194,070 Giannini Mar. 19, 1940 2,231,479 Perry Feb. 11, 1941 2,269,284 Olson Jan. 6, 1942 2,371,951 Cook Mar. 20, 1945 

